Bung drum made of plastics with one or more bung openings

ABSTRACT

A plastic bung drum is provided with a mouth portion made integral with the body of the drum. The circumferential edge of the mouth portion is bent to form an inwardly projecting lip, while an intermediate section of the mouth is provided with an inwardly projecting circumferential bulge, forming a bead. A closure which fits into the mouth of the drum has its opposite edges bent to form outwardly extending circumferential lips, and is provided with a pair of intermediate circumferential flanges which, with the adjacent lips, form a groove at each end of the closure. These grooves engage the inwardly extending circumferential lip and bead on the drum. A peripheral weld is then made to produce a secure, substantially inseparable joint between the inwardly bent lip on the mouth of the drum and the corresponding lip on the closure.

United States Patent Hammes [451 Oct. 7, 1975 BUNG DRUM MADE OF PLASTICSWITH ONE OR MORE BUNG OPENINGS [76] Inventor: Wilhelm Hammes,Haupstrasse 38,

5302 Much, Germany [22] Filed: Nov. 27, 1973 [21] Appl. No.: 419,241

[30] Foreign Application Priority Data 3,458,079 7/l969 Gasbarra 220/60R 3,520,441 7/l970 Fitzgerald 220/60 R 3,53l,0l3 9/1970 Hammes 220/55 AN3,770,!2] ll/l973 Manuel 220/60 R 3,792,797 2/1974 Mrusck et al. 220/60R Primary ExaminerWilliam l. Price Assistant Examiner-J0seph M. Moy

Attorney, Agent, or FirmBurns, Doane, Swecker & Mathis [57 ABSTRACT Aplastic bung drum is provided with a mouth portion made integral withthe body of the drum. The circumferential edge of the mouth portion isbent to form an inwardly projecting lip, while an intermediate sectionof the mouth is provided with an inwardly projecting circumferentialbulge, forming a bead. A closure which fits into the mouth of the drumhas its opposite edges bent'to form outwardly extending circumferentiallips, and is provided with 'a pair of intermediate circumferentialflanges which, with the adjacent lips, form a groove at each end of theclosure. These grooves engage the inwardly extending circumferential lipand bead on the drum. A peripheral weld is then made to produce asecure, substantially inseparable joint between the inwardly bent lip onthe mouth of the drum and the corresponding lip on the closure.

3 Claims, 1 Drawing Figure U.S. Patent Oct. 7,1975

BUNG DRUM MADE OF PLASTICS WITH ONE OR MORE BUNG OPENINGS RELATION TOOTHER CASES This application is a continuation-in-part of copending U.S.application Ser. No. 362,316, filed May 2], 1973.

BACKGROUND OF THE INVENTION Plastic bung drums are commerciallyavailable articles. They are typically made in one piece by ablowmolding method, whereby one or two bungs or stoppers are providedfor in the mold parting line.'These stoppers are usually located incorresponding recesses of an end closure so as to provide a flatstacking surface. For reasons of stress distribution under a stackingload, such drums, in most cases, are made with a slight bulge and, atthe transition to the lower and upper end closure, they have relativelylarge radii. Such drums, with their contours rounded and smooth on allsides, are very difficult to handle as compared with metal drums whichare provided with recessed bottoms and a folded edge, as is prevalent inthe case of drums holding large volumes. The customary molded grippingtroughs at the upper end of the jacket offer only an insufficientpossibility for handling, and they weaken the statics of the drum in anunjustifiable manner.

One solution which has been proposed was to provide a crane ring on theupper closure. Such a device, however, is not suitable for frequentmanipulation by hand. Moreover, the upper closure of such a drum whoseflat surface is broken by the crane ring does not have the requiredstrength in the case of a strain induced during falling.

Furthermore, bungs or stoppers formed by blow molding of the hotmaterial cannot be produced with the necessary precision because of theshrinking process and tensions which develop during cooling. By thismethod, crooked or oval bung holes are produced which require bungs ofspecial design to bridge the clearances, with the result that it is notpossible to use many of the existing devices for filling, closing,sealing, and emptying of drums. The upper end closure, which may beuneven for the same reason is, moreover, more subject to abrasion, andthus does not permit marking with the designation of the contents andwith instructions for use. Likewise, the frequently used loading bymeans of vacuum lift is impossible because of the uneven upper endclosure.

Another very serious disadvantage of such drums stems from the processof production during which a portion of preformed plastic material issqueezedoff at both ends, welded, and then blown against the inside wallof the mold. As a result of the squeezing at the two ends, this preformis no longer rotationally symmetrical at the critical points, causingvariations in the thickness of the wall during blowing because of unevenstretching of the material. These differences can range within an orderof magnitude of 1:3. Such differences in the thickness of the wall occurin an extreme form on the upper end closure, in particular, where forthe purpose of forming bungs lying close to the edge, the preformed massmust additionally be expanded. Therefore, in order to fulfill therequirement for a minimum thickness of the wall in the case ofdrumsproduced in this way, a disproportionally high consumption of materialis required which, besides introducing considerable additional costs,also reduces the efficiency of production.

It was then discovered that drums, with approximately fully open tops,where the preformed mass is squeezed off only at the lower end closure,have a considerably better distribution of wall thickness and can beproduced considerably faster.

On such drum is disclosed and claimed in the alreadymentioned copendingU.S. patent application Ser. No. 362,316, filed May 21, 1973, whosedisclosure is hereby incorporatediby reference.

In general, the copending application discloses an open-end drum whichcan be blow molded from a thermoplastic resin, such as a high density,high molecular weight polyethylene. The top of the open end is bentinwardly substantially at right angles to the axis to form a mouthcomprising a circular, flat, horizontal lip having a diameter smallerthan that of the main body of the drum. Just below the bent-in lipportion, the drum is circumferentially recessed to form a bead-likebulge which is also of smaller diameter than the main body of the drum.The inwardly bent lip and the circumferential bead together give themouth at the top of the drum an S-like cross section.

The drum is provided with a separate extruded closure portion,preferably of the same thermoplastic material, and is made to fit insidethe mouth of the drum. This closure has a recessed bottom in which areformed one or more bung holes. The depth of the closure portion is, ingeneral, governed by the depth of the mouth of the drum, which is tosay, the vertical length of the S-shaped formation.

The upper edge of the closure portion is bent outwardly to form a firstflat, circular rim or lip which is adapted to rest on the inwardlyextending upper lip of the drum, while the bottom edge of the cover isbent outwardly to contact the lower anticlinal surface of the bead onmouth of the drum. Together, the two outwardly bent lips of the closureportion encompass the entire S-formation at the top of the drum. Inaddition, the closure portion is provided with a pair of parallel,circumferential flanges which, with their adjacent outwardly bent lips,respectively form grooves to receive the inwardly bent lip and bead ofthe drum. The groove which receives the bead is of such dimensions thata tight fit is provided. However, the upper groove is slightly deeperthan the length of the lip at the upper edge of the drum.

Prior to assembly, a gasket of appropriate thickness is inserted in theupper groove. The drum is warmed to soften and expand the plasticmaterial to enable the cover to be inserted and for the lip and bead tobe inserted in their respective grooves. Upon cooling, the drum shrinksand forms tight, substantially inseparable joints which resistdeformation by the various stresses to which the drum may be subjectedduring handling and storage.

Although the drum construction just described, which is the subject ofthe previously identified copending U.S. patent application, has solvedmany of the difficulties encountered in the use of plastic drums, thereare situations in which it would be advantageous tohave a bung drumwhich is sealed on all sides and along all edges formed by joined partsand which does not have any gasket between the body of the drum and thecover.

PRINCIPAL OBJECTS AND BRIEF DESCRIPTION OF THE INVENTION One object ofthe present invention is to provide a plastic bung drum combinationassembled from separate drum-body and closure, portions which does notpresent visible joint edges at the assembly sites,

Another object is to provide such a plastic bung drum combination inwhich the joint edges are sealed.

A further object is to provide such a plastic bung drum combination inwhich the use of gaskets is dispensed with in assembling the drum.

These and other objects which will become apparent to those skilled inthe art are achieved in accordance with the present invention.

In general, the above objects are achieved through a significantmodification of the drum described in the copending application.

The body portion of the bung drum of the present invention also is madeof thermoplastic material, such as, for example, polyethylene, and isadvantageously produced by the blow-molding method, leavingapproximately a full opening at the upper edge of the body of the drum.

The upper end of the body portion, constituting the mouth of the drum,has a recessed circumferential bead and an inwardly bent edge or lipwhich, preferably, is of one piece with the body of the drum and is ofthe same thickness.

Basically, the mouth portion can have any desired shape as long as ithas a recessed bead and an inwardly V bent outer edge or lip. For thispurpose, the upper por tion of the body of the drum, constituting themouth,

is molded toprovide a recessed external circumferential groove whichresults in an inwardly projecting cir cumferential bead on the insidesurface of the. mouth of the drum. The wall of the drum then arches outwardly, in the direction of the upper edge to forman external head. Thelatter is bent inwardly at right angles to the axis of the drum. Theresult of the sequence of recessed bead, outwardly arched bead, andinwardly bent upper edge is to form a mouth having a vertical S- shapedcross section.

The recessed groove, together with the overhanging externally archedbead, form a secure gripping surface for handling the. bung drum. Byproviding'a series of axially disposed ribs or corrugations in theexternal surface of the outwardly arched head, the safety and securityof the gripping surface can be greatly augmented.

The cover for the drum according to the present improvement, isessentially the same as that in Ser. No. 362,316. Thus, as-in theearlier case, circumferential grooves on the injection molded coverengage the inwardly bent edge and the recessed bead on the mouth at thetop of the drum which is heated prior to assembly. However, according tothe present invention, no gasket is inserted in the upper groove on thecover. The relative depth of that groove and width of the inwardly bentlip of the drum body portion are such that the lip completely fills thegroove, providing an extremely rigid and inseparable joint when the drumis cooled after assembly. Similarly, the recessed lower bead on the drumfits tightly against the walls of the lower groove on the cover.

In accordance with the present invention, in order to eliminate theexternal, visible joints, the joint formed by the inwardly bent lip onthe drum body portion and the overlapping, outwardly bent rim or lip ofthe upper groove on the cover. is sealed by welding these overlap-' pingparts. This is accomplished in a known manner by the spin-weldingprocess or by means of a heated wire. The bead deposited by the weldingprocedure should, preferably, extend almost to the bend at the upper endof the drum.

Welding the mouth of the drum to the cover further cially counteractsthe feared distortions which occur when the drum is dropped. Whenevertheclosure portion is produced by injection molding, the bung holes are ofa much higher precision and permit the use of standard bung plugs andsealing caps. Moreover, they are protected duringthe insertion of theclosure. The

latter, for its part, is completely even and thus can also takemarkings.

Even in case of the bung drum of the present invention, the effect isutilized that blow-molded hollow bodies made of thermoplastic materialhave a considerable linear shrinkage, which can be precisely determinedand controlled by partial control of the injection temperature andvariation of thethickness of the wall. This shrinkage may. amount to upto 3% of the diameter in case of a circular cross section. Thus, forexample, in the case of a drum opening of 500 mm diameter, there resultson both sides an engagement of 7.5 mm between the upper lip of the drumand the. groove on the closure, a dimension which is entirely sufficientto provide 7 'a safe connection of the two parts, especially whenevercause of lower weight of the body of the drum. Thus,

despite the separate manufacture of the closure by injection molding,considerable technical advantages result.

THE DRAWING In order that the invention may more readily be understoodby those skilled in the art, reference is now made to the single FIGUREof drawing in which there is shown a longitudinal cross section of anupper portion of the drum and cover.

Referring to the drawing, it will be seen that the body l of the drum isintegral with the S-shaped mouth portion 2. The mouth has an inwardlyprojecting, bead-like.

bulge 3 and an inwardly directed edge 4, which is separated from thebead-like bulge 3 adjacent an outwardly arched groove 5.'The bead-likebulge 3 forms a recessed groove 18 on the outside, which serves as agripping recess. In addition, the outside of the mouth is provided witha plurality; of ribs or corrugations 17. As

seen in the drawing, recessed cover portion 6 is provided with thegrooves 9 and 8 on the outside surface of the rim 7, which grooves aredefined by a first circumferential flange l2 and first outwardly bentlip 13, and by a second circumferential flange l1 and second outwardlybent lip 10, respectively. The inwardly bent lip 4 engages flush on allsides with the groove 9. In other words, as will further be apparentfromthe drawing, the first circumferential flange l2 and first outwardlybent lip 13 on the closure portion 6, extend radially outward beyond theradial inner extent of inwardly bent circumferential lip 4 of the drumbody portion so that flange l2 and lip 13 firmly engage substantiallyall of the area of the opposite longitudinally spaced surfaces on lip 4.The flanges 11 and l2are connected by a plurality of ribs at intervals.A bung hole 16 is provided in the opening in cover 6.

i In order to establish the connection between the body 1 of the drumand closure 6, the latter is inserted into warmed mouth 2 in such a waythat the bulge 3, projecting inwardly, and the inwardly bent lip 4 ofmouth 2 will snap into the grooves 8 and 9, respectively of the rim 7 onthe cover 6. In the subsequent cooling of mouth 2, the latter willshrink to such degree that the projecting bulge 3 is pressed firmly intothe groove 8 and the inwardly bent lip 4 is pressed into the groove 9.The trimmed and thus completely smooth front surface of lip 4 at thesame time is pressed firmly against the base of groove 9, so that a safesealing of the connection is assured. The outwardly arched groove 5 ofneck 2 is filled up by the two flanges 11 and 12 of the grooves 8 and 9which, for the purpose of reinforcement, are connected with a number ofribs 15, disposed at a distance from one another. The second outwardlybent lip 10 and second circumferential flange 11 which define the groove8 are seen from the drawing to extend radially outward beyond the radialinner extent of bulge 3 such that the second flange and the second lipfirmly engage opposite longitudinally spaced surfaces 21 and 22,respectively, of bulge 3. Corrugation 17 on neck 2 provides a grippingsurface and thus improves ones ability to handle the drum. Recess 18,together with corrugations 20 on cover 6 further improve the ability toobtain a secure grip on the drum during handling.

Finally, the outside edge of the outwardly bent, lip 13 of the closureportion is welded by means of seam 19 to the inwardly bent lip 4 nearthe point of the bend, to produce a unitary structure.

The invention, as described above, provides a drum which is completelyclosed on all sides and edges and which requires no gasketsbetweenthebody of the drum and the closure. The absence of resilientgaskets and the manner in which the closure is secured in the mouth ofthe drum results in a rigid, nondeformable structure which is augmentedby the welded seam between the cover and the mouth. This not onlyincreases the rigidity of the mouth area, but also provides the mostpossible seal against possible leaking of the contents.

Although the drawings described above show the preferred structure forthe drum according to the present invention, it will be obvious to thoseskilled in the art that the design of the interacting elements of theneck of the drum and of the cover can be varied without departing fromthe spirit of the invention.

What is claimed is:

1.,A drum of the type having a plastic body portion and a separateplastic closure portion firmly seated within an end of the body portioncomprising the combination of:.

a. a body portion having a mouth portion at one end thereof, said mouthportion having 1. an inwardly projecting circumferential bead-likebulge, said bulge defining a generally radially inwardly projectingannular gripping recess,

2. an inwardly bent circumferential lip located outwardly of said bulgerelative to a longitudinal axis of the drum, and

3. an intermediate section extending between said bulge and said lip anddefining a generally radially outwardly projecting annular first groove;and

b. a plastic end closure for said mouth portion having circumferentialmargin means firmly anchored within the mouth portion of said bodyportion to resist distortion of the latter while preventing removal ofsaid end closure from said body portion, said margin means comprising 1.an outwardly-bent circumferential lip at each end,

2. a first circumferential flange forming, with a first of saidoutwardly bent lips, a first groove engaging and seating the inwardlybent circumferential lip of the mouth portion of the drum, said firstcircumferential flange and said first outwardly bent lip extendingradially outward beyond the radial inner extent of the inwardly bentcircumferential lip on the mouth portion of the drum body portion suchthat said first circumferential flange and said first outwardly bent lipfirmly engage substantially all of the area of the oppositelongitudinally spaced surfaces on said inwardly bent circumferentiallip, the inwardly bent circumferential lip extending into said firstgroove the entire depth thereof, and

3. a second circumferential flange forming with the second of said lipsasecond annular groove engaging and seating the inwardly projectingcircumferential bead-like bulge of the drum, said second circumferentialflange and said second lip extending radially outward beyond the radialinner extent of said bulge such that said second flange and said secondlip firmly engage opposite longitudinally spaced surfaces of said bulge,said engagements forming substantially inseparable joints; and

c. a peripheral bead of material forming a weld joining the peripheraledge of the first of said lips of the closure portion and saidinwardly-bent circumferential lip of the mouth portion of the drum.

2. A drum according to claim 1 wherein the end closure is provided withone or more bung holes.

3. A drum according to claim 1 wherein the mouth portion, including theinwardly bent circumferential lip and the inwardly projectingcircumferential bead-like bulge, is formed integral with the bodyportion of the

1. A drum of the type having a plastic body portion and a separateplastic closure portion firmly seated within an end of the body portioncomprising the combination of: a. a body portion having a mouth portionat one end thereof, said mouth portion having
 1. an inwardly projectingcircumferential bead-like bulge, said bulge defining a generallyradially inwardly projecting annular gripping recess,
 2. an inwardlybent circumferential lip located outwardly of said bulge relative to alongitudinal axis of the drum, and
 3. an intermediate section extendingbetween said bulge and said lip and defining a generally radiallyoutwardly projecting annular first groove; and b. a plastic end closurefor said mouth portion having circumferential margin means firmlyanchored within the mouth portion of said body portion to resistdistortion of the latter while preventing removal of said end closurefrom said body portion, said margin means comprising
 1. anoutwardly-bent circumferential lip at each end,
 2. a firstcircumferential flange forming, with a first of said outwardly bentlips, a first groove engaging and seating the inwardly bentcircumferential lip of the mouth portion of the drum, said firstcircumferential flange and said first outwardly bent lip extendingradially outward beyond the radial inner extent of the inwardly bentcircumferential lip on the mouth portion of the drum body portion suchthat said first circumferential flange and said first outwardly bent lipfirmly engage substantialLy all of the area of the oppositelongitudinally spaced surfaces on said inwardly bent circumferentiallip, the inwardly bent circumferential lip extending into said firstgroove the entire depth thereof, and
 3. a second circumferential flangeforming with the second of said lips a second annular groove engagingand seating the inwardly projecting circumferential bead-like bulge ofthe drum, said second circumferential flange and said second lipextending radially outward beyond the radial inner extent of said bulgesuch that said second flange and said second lip firmly engage oppositelongitudinally spaced surfaces of said bulge, said engagements formingsubstantially inseparable joints; and c. a peripheral bead of materialforming a weld joining the peripheral edge of the first of said lips ofthe closure portion and said inwardly-bent circumferential lip of themouth portion of the drum.
 2. an inwardly bent circumferential liplocated outwardly of said bulge relative to a longitudinal axis of thedrum, and
 2. A drum according to claim 1 wherein the end closure isprovided with one or more bung holes.
 2. a first circumferential flangeforming, with a first of said outwardly bent lips, a first grooveengaging and seating the inwardly bent circumferential lip of the mouthportion of the drum, said first circumferential flange and said firstoutwardly bent lip extending radially outward beyond the radial innerextent of the inwardly bent circumferential lip on the mouth portion ofthe drum body portion such that said first circumferential flange andsaid first outwardly bent lip firmly engage substantialLy all of thearea of the opposite longitudinally spaced surfaces on said inwardlybent circumferential lip, the inwardly bent circumferential lipextending into said first groove the entire depth thereof, and
 3. anintermediate section extending between said bulge and said lip anddefining a generally radially outwardly projecting annular first groove;and b. a plastic end closure for said mouth portion havingcircumferential margin means firmly anchored within the mouth portion ofsaid body portion to resist distortion of the latter while preventingremoval of said end closure from said body portion, said margin meanscomprising
 3. a second circumferential flange forming with the second ofsaid lips a second annular groove engaging and seating the inwardlyprojecting circumferential bead-like bulge of the drum, said secondcircumferential flange and said second lip extending radially outwardbeyond the radial inner extent of said bulge such that said secondflange and said second lip firmly engage opposite longitudinally spacedsurfaces of said bulge, said engagements forming substantiallyinseparable joints; and c. a peripheral bead of material forming a weldjoining the peripheral edge of the first of said lips of the closureportion and said inwardly-bent circumferential lip of the mouth portionof the drum.
 3. A drum according to claim 1 wherein the mouth portion,including the inwardly bent circumferential lip and the inwardlyprojecting circumferential bead-like bulge, is formed integral with thebody portion of the drum.